Heavy Metals Flashcards Preview

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Flashcards in Heavy Metals Deck (22):
1

potential routes of exposure to heavy metals?

skin
ingestion
inhalation
ocular

2

what does LD50 stand for?

median lethal dose
causes death in 50% of the group given toxic substance
the lower the LD50= THE MORE TOXIC IT IS

3

five mechanisms of toxicity for heavy metals?

1. enzyme/cofactor inhibition or potentiation
2. disruption of membrane and other transport processes
3. disruption of mitochondrial function--> fatigue
4. decreased neuronal function and nerve conduction
5. bind sulfhydryl groups on proteins and a.a.s

4

how are people exposed to lead?

home: dust, paint, soil, imported remedies, some cosmetics, miniblinds, metal wicked candles
work: swallowing lead dust, contaminated air, contact, bring home from work
hobbies: car repair, artistic painting, stained glass, pottery glazing, soldering, target shooting, making bullets, slugs or fishing sinkers
drinking water: boiling does not get rid of!
products: computers, solder, pewter, ceramic glazers, jewelry, automotive batteries, imported or older pre-regulation products
environment: soil near roadways, businesses with lead

5

what population is at most risk for adverse effects dt lead exposure?

children living in older houses
PG women and the developing fetus

6

health effects of lead?

most excreted but that which is not can move between blood, soft tissues and mineralizing tissues
affects all organ systems
developmental: crosses placenta, neurological effects on kids
neuro: targets hippocampus, decreases ASA activity
endocrine: effects vit D levels, may alter thyroid fxn w/chronic exposure
cardio: increases risk of HTN

7

lead poisoning mechanism?

interferes w/heme synthesis by diminishing delta-ALA dehydratase activity= microcytic, hypochromic anemia w/basophilic stippling

8

ssxs of lead poisoning?

irritability
anorexia
malaise
H/A
constipation
abd pain
renal toxicity
acute lead encephaloptahy

9

how to best test for lead levels in the body?

BLOOD
adults: should be less than 20 mcg/dL
children: should be less than 5 mcg/dL

10

how do you manage lead toxicity?

remove exposure to toxic substances
chelation: if very high blood levels
eat diet high in calcium and iron as these displace lead

11

major source of mercury poisoning for the population at large?

inhalation of elemental mercury volatilized from dental amalgams

12

3 forms of mercury

elemental mercury
organic: methylmercury, ethylmercury
inorganic: mercuric chloride, mercuric sulfide

13

where do you find methylmercury? what can it cause?

find when person has eaten large amounts of fish over weeks to months - 95% comes from food
damages nervous system, infants can be born with cerebral palsy --> all because can cross the BBB

14

where do we get exposure to ethylmercury from?

break down of thimerosal
excreted from body more quickly than methyl

15

where are inorganic mercury forms mostly found?

skin lightening creams
should be less than 5 microg/L

16

predominant commercial use of cadmium?

battery manufacturing

17

airborne cadmium exposure occurs via what substances? can also be found where

burning fossil fuels
incineration of multiple waste materials
zinc, lead, copper or smelters
cigarette smoke inhalation
can also be found in the soil- has a high rate of transfer to plants such as cereal grains, wheat, rice, potatoes and seeds

18

health effects of cadmium exposure?

can lead to iron deficiency
decreased olfactory fxn
accumulates in liver and KDs (irreversible proteinuria and progressive reduction in GFR) where it binds to metallothionein
can result in painful osteomalacia or osteoporosis
severe pneumonitis
emphysema
associated with lung CA
reproductive and teratogenic effects, increase in endometrial CA, may have a role in prostate CA

19

historical uses of arsenic?

medicines, cosmetic lighteners, paint pigments, wood preservation

20

two forms of arsenic? which is more toxic?

organic: excreted quickly via urine
inorganic is MUCH MORE toxic- well absorbed from GI tract, come from water, cigarette smoke and poultry

21

health effects of inorganic arsenic on the body?

inhibition of numerous enzymes, substitution in phosphate metabolism, interference in signal transduction pathways, alters gene expression

22

3 provocative chealtors?

DMSA
DMPS
EDTA